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A FACTOR FROM NORMAL TISSUES INHIBITING TUMOR GROWTH
1Laboratories of The Rockefeller Institute for Medical Research.
Abstract:
Extracts of desiccated embryo skin and placenta have been found to exert a definite retarding action on the growth of two transplantable carcinomas of mice, but they were without effect on sarcomas. In tests involving some 828 inoculations of the tumor cells and the extracts, complete suppression of growth occurred in from 55 to 71 per cent of instances, as compared with 21 to 27 per cent in the controls, and where growth was not completely suppressed some retardation was found in practically every instance. To judge from findings in rabbits the inhibitor is not demonstrable in the placenta until the beginning of the second third of pregnancy, reaches its maximum by the last third, but disappears about 2 or 3 days before term. Extracts of fresh placenta are without effect, and no very definite inhibition was noted in extracts of a variety of other desiccated or fresh tissues. The conclusions here reported are based on the results of over 3800 inoculations.
Insights
Embryo skin and placenta extracts significantly inhibit mouse carcinoma growth, with notable retardation in most cases. This anti-tumor effect, observed in over 3800 inoculations, shows promise in cancer research.
Area of Science:
- Oncology
- Biochemistry
- Developmental Biology
Background:
- Transplantable carcinomas and sarcomas in mice are common models for cancer research.
- Placental and embryonic tissues are known to contain biologically active compounds.
- Previous research has explored the anti-proliferative effects of various natural extracts on tumor growth.
Purpose of the Study:
- To investigate the effect of desiccated embryo skin and placenta extracts on the growth of transplantable mouse carcinomas and sarcomas.
- To determine the efficacy of these extracts in suppressing or retarding tumor development.
- To identify the gestational stage of placental extract production that yields maximum inhibitory activity.
Main Methods:
- Preparation and extraction of desiccated embryo skin and placenta.
- Inoculation of tumor cells (carcinomas and sarcomas) into mice, followed by administration of tissue extracts.
- Control groups received tumor cells without extracts.
- Observation and quantification of tumor growth suppression and retardation over time.
- Analysis of placental extracts from different gestational periods in rabbits.
Main Results:
- Desiccated embryo skin and placenta extracts demonstrated a significant retarding effect on the growth of two transplantable mouse carcinomas.
- These extracts were ineffective against mouse sarcomas.
- Complete growth suppression was observed in 55-71% of carcinoma instances treated with extracts, compared to 21-27% in controls.
- Partial growth retardation was noted in nearly all cases where complete suppression did not occur.
- The placental inhibitor was detectable from the second trimester of pregnancy, peaked in the last trimester, and diminished near term.
Conclusions:
- Desiccated embryo skin and placenta extracts possess potent anti-carcinoma properties in mice.
- The inhibitory effect is specific to carcinomas and not observed in sarcomas.
- Placental extracts exhibit stage-dependent inhibitory activity, with maximal effect during late pregnancy.
- These findings suggest the presence of a novel anti-tumor agent in placental and embryonic tissues with potential therapeutic applications.
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